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Trouble with sealing jam jars - help needed!

Posted by Jane CH 
Trouble with sealing jam jars - help needed!
November 30, 2009 04:25AM
I need some help with potting jam!

I’ve been using jars with metal twist top caps. The manufacturer’s instructions say to put the lids on, tighten them firmly but not too firmly, turn them upside down, and when cool test to hear a “ping” when you tap on the lid (with say a wooden spoon) rather than hearing a dull noise. If the noise is dull, then a seal hasn’t formed.

I did all of this apart from turning the all the pots upside down but only one of the pots is sealed properly. Does anyone have any suggestions for what I may have done wrong and how to avoid the problem in the future? I did turn one of the pots upside down but that didn’t seal properly either, and of course the jar looks rather messy on the inside now that I’ve turned it the right way up. Surely I wouldn't have to turn all the pots upside down? Did I not work quickly enough to keep everything hot?

Apologies if this has been asked and answered in another posting but the search function didn't find anything for me.
Re: Trouble with sealing jam jars - help needed!
November 30, 2009 05:22AM
Were the jars and the jam both hot when you put the lids on? It is the contraction of the cooling air above the jam that causes the lid to seal.
Re: Trouble with sealing jam jars - help needed!
November 30, 2009 06:02AM
Penny, thanks for replying.

The jars were certainly hot, but I can't remember how hot the lids were. I had taken the lids & jars out of the oven at the same time, filled six jars, cleaned the tops, then put the lids on. I think you are saying that the lids should be hot too - I should leave the tops in the oven until actually putting them on?
Re: Trouble with sealing jam jars - help needed!
November 30, 2009 06:34AM
i made Raspberry jam today and put it into cold but sterilised jars. Is this going to matter? Should they have been hot? As I had to cool the jam for 20 mins I didnt think It would be a problem.I have put screw tops back on once they had cooled completely.
Re: Trouble with sealing jam jars - help needed!
November 30, 2009 06:47AM
But, does it matter if the jars haven't sealed properly? Once upon a time we only used celophane (or brown paper in even earlier days) to cover the jam in jars (not lids) and the jam rarely went off. Sometimes there was a bit of mould on the jam when it was initially opened, but scoop that off and the rest of the jam was fine!

I now always use pre-used jars with lids and use them over and over again each year. The jars I wash and steralize with heat in the oven. The lids I wash and also put them into the oven to heat through. I fill and screw down the lid one jar at a time.
Regards,
Dawn.
Re: Trouble with sealing jam jars - help needed!
November 30, 2009 07:24AM
hello Jane, why do you think that your jars aren't sealed properly?
If the lids have a pop top, it should be concave. I find the tap test too subjective (maybe I'm tone deaf)!
I fill my jars right up to the top as far as possible without spilling and don't bother heating the lids, just sterilise them by immersing in boiling water and drip drying on a clean tea towel. The jars go into the oven at 50C. Inverting the jars sterilises the tops again anyway. I only leave jars of marmalade inverted (to stop the peel rising to the top) and only till they're almost but not quite set - otherwise you end up with an air bubble at the bottom of the jar. My apricot, plum and strawberry jams are inverted and left to cool right side up. As they cool, you can usually hear the vacuum form as the lid pops when the jam cools sufficiently. Similiarly, when you do open the jars, their should be a pop as the vacuum is broken
Re: Trouble with sealing jam jars - help needed!
November 30, 2009 03:03PM
I think the jars failed to seal because you put the lids in the oven, thereby destroying the little bit of 'rubber' seal in them. An oven is far too hot for this job, a simple rinse under the tap and then pour over some boiling water and immediately drain them. Turn them all up the right way, without touching the inside, and allow plenty of time for them to dry naturally, no wiping with a tea towel. You will have sterile tops with the seal still intact.
Re: Trouble with sealing jam jars - help needed!
November 30, 2009 05:16PM
Dawn it is interesting that your comment has come up. I always use "recycled" jars too but I am beginning to wonder if the glass is not so strong in quality in newer jars. Last night I was opening a screw top jar, the seal was not stuck tight, and the whole top of the jar screwed off in my hand! At first I was too scared to look at my hand to see if it was still there, luckily the resulting injury was not too bad- no stitches just great first aid performed by my son.Hopefully it was just a one off, but in future I will wrap jars before I open them- I am such a coward.
Re: Trouble with sealing jam jars - help needed!
November 30, 2009 05:21PM
Thanks everyone for their replies so far, and Penny I see I misread your reply. The jars and the jams were both hot when I filled them, and the lids were hot when I got them out of the oven but probably had cooled down a little by the time I got to put them on.

I know that the jars didn’t seal properly because of the dull sound when tapped and because the lid wasn’t sucked down a little in the centre like the lid on the jar that had properly sealed. I do want to make sure that I seal them properly as if I end up selling jams at a local market I don’t want to jams to go off after I’ve sold them!

I’ll try another lot tomorrow, and will try using (a) hot lids that I’ve got straight out of the oven but (b) which I haven’t left in the oven for very long. Hopefully that will mean that the vacuum will occur but that I haven’t destroyed the rubber innards of the lids.
Re: Trouble with sealing jam jars - help needed!
November 30, 2009 05:36PM
I don't heat my oven to much over 50oC and I have had no problems with the rubber inside the lids destructing. If anything I have trouble opening the jars and they get a few dents in the sides of the lids from having to tap them to wake them up to opening!! Probably someone is going to tell me that at 50oC I'm not sufficiently sterilizing the jars and lids? I don't have problems with the jam going off and we've survived this length of time so far! They get a full wash in the diswasher before being transferred to the oven and there they stay heated until such time as the jars are ready to be filled.

Stephanie - I'm so pleased you still have two hands after that unfortunate accident. That's scary really and would not give much confidence in reusing the jars. I've never had that happen and hope I never will. I had a glass shelf in my china cabinet break, it broke dead centre and when I went to get replacement glass shelf the guy told me that with trucks etc. that go past it does have an effect on the glass i e it weakens it - you can hear the vibration sometimes as the crockery can rattle when a heavy vehicle uses the road and this is an old villa with wooden floors so the whole house feels the effect! Thank goodness the road at the moment is pretty smooth which makes a big difference.

Jane I can understand your concern - I would be the same especially if you are selling or giving the filled jars away. I hope you have success with your jam making tomorrow. The vacuum occurs as the jam is cooling down in the jar.
Regards,
Dawn.



Edited 1 time(s). Last edit at 11/30/2009 05:38PM by Dawn.
J1
Re: Trouble with sealing jam jars - help needed!
November 30, 2009 05:40PM
I used to do a lot of preserving and jam making. I'd put the preserving lids in a bowl and pour boiling water in, then remove them with tongs (boiling water over them too) as and when I needed them for the jars. They were the Agee preserving lids, with the rubber seal and the screw ring. For jam, I used the cellophane circles and rubber bands, no sterilising, just wetting slightly with tap water as per instructions on the packet. No problems.

(Jars were heated in the oven and removed several at a time when I was ready to pour the hot mixtures in, with the lid going on immediately after.)
Re: Trouble with sealing jam jars - help needed!
December 01, 2009 05:11PM
Here's a hint for lids stuck on jars: put some very hot water into a container which will fit the jar, hold the jar upside down with just the lid in the water. Keep it there for about 10 seconds, just long enough to expand the lid and not the glass top of the jar. Use a damp cloth to grasp the lid and turn. It should come off easily enough without having to tap the jar on a solid surface.
Re: Trouble with sealing jam jars - help needed!
December 01, 2009 05:34PM
Thanks (again!) Lorna - shall try that. I have a weak wrist so struggle a bit opening jars if they're extra tight and not always is my husband around at the right time to use his iron grip!
Regards,
Dawn.
Re: Trouble with sealing jam jars - help needed!
December 02, 2009 06:12AM
hello Dawn, my hubby bought me a jar opening contraption for Xmas ages ago and it's wonderful not having to track him down to open those really widemouthed jars that my fingers barely wrap around. It's a strip of heavy rubber (of a similar texture to the rubber gaskets on clip top preserving jars) that's threaded through a plastic handle. The rubber can be adjusted to any diameter jar and really works a treat. Sadly, he can't remember where he bought it but if you search boa jar opener on trademe, there's one for sale at the moment with pictures. I have the larger version.
Re: Trouble with sealing jam jars - help needed!
December 02, 2009 03:45PM
Thanks Lorna for the tip. The lid of the jar I tried to open wasn't stuck, I had just got it out of the cupboard and was gently opening it. If it had been stuck I would not have got cut as it would have been wrapped in a towel, for grip, and I would have been using my opening thingy.
Re: Trouble with sealing jam jars - help needed!
December 02, 2009 04:21PM
If you Google 'jar openers' and click on 'images' you will see there is a plethora of styles available, from the simplest similar to the one meganp describes, to battery operated ones and to really fancy electric ones. I have one, similar to a set of pliers with multiple sized toothed 'lid-grips' which I find invaluable.
Re: Trouble with sealing jam jars - help needed!
December 02, 2009 04:25PM
Hello Megan,
Thank you very much for your information - I've looked up the Boa Constrictor (love the name) on Trade-me and now I know what I'm looking for will try to source one in shopping malls and the like - I would like to find the larger version if I can as well. Kitchen shops may be a good start.
Grateful thanks,
Dawn.
Re: Trouble with sealing jam jars - help needed!
December 02, 2009 04:51PM
I tried again with my jam making & pot sealing efforts last evening ... and this time got three out of six jars to seal. Better than my previous effort of one out of five, but still not good enough! I think that I was so nervous about overtightening the lids – which according to the manufacturer can cause the lugs on the lids to bend – that I didn’t tighten them enough and so air must have escaped rather than forming a vacuum. I only potted one or two at a time and kept everything very hot.

I will keep trying, and now have some good tips on ways to remove the lids if they are too tight!
Re: Trouble with sealing jam jars - help needed!
December 02, 2009 05:02PM
I screw the lids on as tight as I can (that's probably why I have a weak wrist!). And, if it hasn't already been mentioned, it pays to wipe (with a damp clean paper towel) the rims of the jars after filling with jam to remove any spillages, especially where the thread of the lid goes. Berry jams which have their little seeds can be a problem when it comes to sealing if the seeds are in the way of getting a good seal.

At least you did much better this time because three out of six has got to be better than nil out of six!
Regards,
Dawn.



Edited 1 time(s). Last edit at 12/02/2009 05:03PM by Dawn.
Re: Trouble with sealing jam jars - help needed!
December 02, 2009 10:37PM
I find it useful to do the upside down thing because it certainly does tell you if the lids are on tight enough or not! - as well as sterlising the tops with the hot jam. I leave them upside for maybe 30mins then turn them right side up. Usually they are still warm so everything settles nicely and the tops suck down as they continue to cool.

-Fiona
summerfieldsfoods.co.nz
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